The present invention relates to a magnetic disk drive and, more particularly, to a magnetic disk drive of the type using a magnetic disk covered with a film of liquid lubricant for obviating wear ascribable to the friction and contact of the disk with a magnetic head.
A magnetic disk mounted on a magnetic disk drive as a recording medium has customarily been covered with a film of perfluoropolyether (PFPE) or similar liquid lubricant. The film of liquid lubricant protects the disk from wear ascribable to friction and contact of the disk with a magnetic head. It is a common practice to mount a stack of magnetic disks on a magnetic disk drive, as taught in, e.g., Japanese Patent Laid-Open Publication No. 61-9818. Such magnetic disks are mounted on a single spindle at a small spacing in order to increase the capacity of the disk drive.
The problem with the magnetic disks of the kind described is that the liquid lubricant is scattered around due to centrifugal force while the disks spin, reducing the thickness of the films. The decrease in the thickness of the films is accelerated by the shearing forces of air streams flowing on the surfaces of the disks. The decrease in the thickness of the films directly translates into the decrease in the lubricating effect expected to obviate the wear. As a result, the disks wear due to friction acting between them and magnetic heads and the contact of the former with the latter. This causes information stored in the disks to be lost.